2023-05-09 ニューサウスウェールズ大学(UNSW)
◆ラットを使った実験では、高脂肪・高糖質な食事を16日間続けた結果、それを長く繰り返すほど、空間的な記憶に悪影響が及び、腸内細菌叢の多様性が減少し、肥満に関連した「悪い」細菌のレベルが高まり、「良い」細菌のレベルが低下したことが明らかになった。
◆炎症や脳機能の構造的変化も原因の1つだとされ、健康的な食事を継続することが脳の健康維持に必要であることが示唆された。
<関連情報>
- https://newsroom.unsw.edu.au/news/health/diet-cycling-impacts-spatial-memory-rat-study
- https://onlinelibrary.wiley.com/doi/10.1002/mnfr.202200809
- https://www.nature.com/articles/s41598-019-50113-3
肥満食サイクルはラットの認知機能および微生物叢組成に段階的な影響を及ぼす Obesogenic Diet Cycling Produces Graded Effects on Cognition and Microbiota Composition in Rats
Michael D. Kendig, Sarah-Jane Leigh, Kyoko Hasebe, Nadeem O. Kaakoush, R. Fred Westbrook, Margaret J. Morris
Molecular Nutrition and Food Research Published: 21 April 2023
DOI:https://doi.org/10.1002/mnfr.202200809
Abstract
Scope
The effects of diet cycling on cognition and fecal microbiota are not well understood.
Method and Results
Adult male Sprague-Dawley rats were cycled between a high-fat, high-sugar “cafeteria” diet (Caf) and regular chow. The impairment in place recognition memory produced by 16 days of Caf diet was reduced by switching to chow for 11 but not 4 days. Next, rats received 16 days of Caf diet in 2, 4, 8, or 16-day cycles, each separated by 4-day chow cycles. Place recognition memory declined from baseline in all groups and was impaired in the 16- versus 2-day group. Finally, rats received 24 days of Caf diet continuously or in 3-day cycles separated by 2- or 4-day chow cycles. Any Caf diet access impaired cognition and increased adiposity relative to controls, without altering hippocampal gene expression. Place recognition and adiposity were the strongest predictors of global microbiota composition. Overall, diets with higher Caf > chow ratios produced greater spatial memory impairments and larger shifts in gut microbiota species richness and beta diversity.
Conclusion
Results suggest that diet-induced cognitive deficits worsen in proportion to unhealthy diet exposure, and that shifting to a healthy chow for at least a week is required for recovery under the conditions tested here.
カフェテリア式食事へのアクセスパターンがラットの脂肪量と空間記憶障害の程度を決定する Pattern of access to cafeteria-style diet determines fat mass and degree of spatial memory impairments in rats
Michael D. Kendig,R. Frederick Westbrook & Margaret J. Morris
Nature Published:18 September 2019
DOI:https://doi.org/10.1038/s41598-019-50113-3
Abstract
Repeated ‘cycling’ between healthy and unhealthy eating is increasingly common but the effects of such cycling on cognitive function are unknown. Here we tested the effects of cycling between chow and a cafeteria diet (CAF) rich in saturated fat and refined carbohydrates on fat mass and place recognition memory in rats. Rats fed the chow diet (control group) were compared with groups fed CAF for either: 3 consecutive days per week followed by 4 days of chow, (3CAF:4CHOW group); 5 consecutive days per week followed by 2 days of chow (5CAF:2CHOW group); or 7 days per week (7CAF group). Total days of exposure to CAF were matched between the latter groups by staggering the introduction of CAF diet. After 16–18 days of CAF, spatial recognition memory was significantly worse in the 7CAF group relative to controls. After 23–25 days of CAF, both the 7CAF and 5CAF:2CHOW groups, but not the 3CAF:4CHOW group, were impaired relative to controls, mirroring changes in fat mass measured by EchoMRI. CAF feeding did not affect object recognition memory or total exploration time. These results indicate that even when matching total exposure, the pattern of access to unhealthy diets impairs spatial memory in a graded fashion.
